Here's an interesting one...Convert LocoSound Tender to work as PS2 tender? Edit: YES!

They're NOT wired the same.

LocoSound Tender (Board in Locomotive)

ProtoSound 2 (5V) Tender (Board in Locomotive)

Thanks a bunch John!  So it looks like:

Pins 1 through 4 are good to go

I 've got to add the battery to pin 6 and tie ground to pin 3,

Leave pin 7 blank (since I won't be using marker lights, which is odd because there are definitely no markers on this tender anyway)

Pin 8 is good

Pull the speaker lead off the existing loco sound ground and connect to pin 9 (does the speaker polarity matter on this?  If it does I need to swap 9 & 10 right?)

Pin 10 is good.

Seems like the toughest part will be re-routing the speaker off the PCB ground to its own negative in the tether somehow.  I don't have the insert tools to crimp a new pin.  I might just run it separately into the loco then.

This is super helpful, and it seems that the basic answer to my question is YES, with a little re-routing, this tender should be OK to use.  Speakers are both 16 ohm, and the "linear taper" potentiometer I assume is the same as the "audio taper" in the locosound.

I'll let y'all know how it goes!

The tools to crimp ins aren't expensive, and you can grab an unused wire from a connector and just splice the wires together and insert that pin.  I believe Digikey even sells crimped wires for most connectors.

The LocoSound speaker is 8 ohms, so you will want to replace the speaker.

I'll look into it, John.  If I remember correctly from a previous project, I had a hard time opening the tether connector to get access to the pins.  I was planning on just swapping out and re-locating the appropriate wires at the soldered board on the loco, but the speaker wire will be the one I have to figure out getting a pinout on the tether.

The diagram above shows 16 ohm on the LocoSound speaker.  Is that a typo?  I'll open my tender later today and see what's actually in there.

You don't have to open the tether connector, all ten wires come out the other end!  Truthfully, I don't see where you need to do any pin swapping, just splice the wires coming out of the tether in the tender to the correct locations.

Thanks John! Love it when a plan comes together!

Little bit of messing with wires, hooked up a homemade BCR, and strung together 3 speakers ( ! ). Needed to get 16 ohms, the loco-sound was only 8 (I guess the schematic is a misprint). So I had two more 4 ohm speakers in hand, just put all 3 in series. And they all fit!

I do have a new 16 ohm on order from parts express... It was 88 cents! I'll put that in as soon as it comes.

But in the meantime, I have a working PS2 turbine! Let's see how long this 5 volt board holds out...

I hate to state the obvious, but the steam turbine doesn't chuff!

Lol, don't really care. But that's the sound file that was in the board, and the chuff sound matches the smoke fan, so no biggie. Are you suggesting that someone at some point put a different PS2 board in? I'd be surprised, because it all looked tied up nice and beat like the factory does it. Didn't look like a replacement.

In any case, whoever did it did a decent job. And I'm not complaining. I don't want to make anyone jealous, but I got this engine for less than I would spend at Skyline Chili on a 3 way and a couple of Coneys for lunch (not exaggerating). So it can chuff all it cares to chuff as far as I'm concerned! 

Actually, that was the original sound file that came with the bantam turbine, MTH obviously didn't do their homework.  The good news is, there is another sound file you can load that has the correct turbine sounds and runs the fan continuously like the real prototype does.

Gunrunnerjohn,  isn't the tach reader different for PS2 and Locosound?

Locosound and PS/2 use the same type of tach reader, there's a resistor on the Locosound models, not sure why they needed that.  However, he started with a PS/2 engine, just a Locosound tender, so that issue never came up.

@351_DD-1: yes, I have PS2 tach system and PS2 smoke, which are both original with the Bantam engine. The tender is the only thing that was loco-sound, and it was just a speaker and a pot.

John, would changing the sound file risk the 5V board in any way? I'd rather do as little handling of the board as possible, some they're liable to blow up at the slightest provocation as far as I can tell from these boards. 

I have a 5 volt board that has smoked twice already and is still useable.  (Front and rear lighting circuits blew).  Maybe this one has nine lives?  Now using the interior light circuit for headlight and tapped off the motor for reverse light.  Always fun to tinker.

@Jeff_the_Coaster_Guy posted:

John, would changing the sound file risk the 5V board in any way? I'd rather do as little handling of the board as possible, some they're liable to blow up at the slightest provocation as far as I can tell from these boards. 

Not any more than running it.  OTOH, I didn't see the file in 5V form when I looked on MTH, so maybe that's not an option.

@351_DD-1 posted:

I have a 5 volt board that has smoked twice already and is still useable.  (Front and rear lighting circuits blew).  Maybe this one has nine lives?  Now using the interior light circuit for headlight and tapped off the motor for reverse light.  Always fun to tinker.

The lighting FET's are not that hard to replace, even on the 5V boards.

It looks like there are two toasted diodes in the center of the bottom board.

Diodes?  The lighting FET's are all on the end of the board.

Ok, two little buggers sitting side by side dead center of shot above coil on left.  Both appear to have a crispy coating.  Everything else on either board looks normal.